Armature backstop



June 19, 1923. 1,459,425

C. H. WHEELER ARMATURE BACKSTQP Filed Jan. 4, 1921 by www Ptenlzecl4 June 19, 1923.

PATENT OFFICE.

cLYnE n. w-IEELER, o MIDLAND PARK Bonoucn, mw mum, 319,303 .m

wns'rnm ELECTRIC COMPANY, mconrona'rnn, or mw Yonx, r. Y., con- PORATION Ol' NEW YORK.

AEMATURE IBACKSTOIP.

Application filed January 4, 1921.

To all whom it may concern:

Be it known that I, CYLDE H. WHEELER, a citizen of the United States, residing at borough of Midland Park, in the county of .l Bergen, State of New Jersey, have invented certain new and useful Improvements in Armature Backstops, of which the following is a full, clear, concise, and exact description. This invention relates to electromagnetic devices, and more particularly, to an improved back stop for the armatures of relays and similar apparatus.

It has' been found that the armatures of message counting registers, such as are used 1' in telephone exchanges for recording calls, sometimes fail to operate due to a gummy deposit Which forms at the point of contact between the armature and its back stop. The gummy deposit, consisting presumably of oil and dust, forms after the registers have been in service a considerable time, in spite of the fact that the registers are covered and reasonably dust-proof.

The invention consists in providing a '25 loosely mounted back stop, which, if it is stuck thereto will follow the armature a short distance on its forward stroke, whereupon the back stop will be suddenly restrained and torn away from the armature.

The pull of an electromagnet on its armature is smallest at the beginning of the forward stroke due to the larger air gap, andV grows stronger as the armature moves for- Ward. It will be apparent, then, that if 85 the armature is stuck to a rigidly mounted back stop, it is likely to entirely fail to move,

especially if only enough current is supplied to the electromagnet to normally op- -\erate the'armature, that is, When it is not 40 stuck.

The invention, while described in connection with a message register, is equally applicable to other e ectromagnetc apparatus, such as relays and step by step devices, and

is not limited to the specific arrangement described, but only by the appended claims.

The accompanying drawing illustrates the invention in connection with a well-known type of messa e register similar to that described in U. Patent No. 765,255 to C. E.

Scribner and F. R. McBert Fig. 1 is a longitudina Section of the seria no. 434,314.

message register along line 1-1 of Fi 2; Fg. 2 s a plan view of the same; andgFig. 3 a partial sectional view illustrating the armature in its actuated position.

Armature 1 is pivotally mounted on the pn 2 and s normally held against the back stop 3 by the coil spring 4. The armature s shown in its normal position in Fi 1 and 2, and in its actuated position ingl fg 3. The electromagnet 5 is adapted, energzation, to actuate armature 1. Steppmg pawl 6 is carried by'armature 1 and arranged to actuate ratchet Wheel 7 upon each forward movement of the armature.

It 1s thought unnecessary to describe the operation of the counting discs 8, as their operation is well-known to those skilled in the art and not pertinent to the present invention. v

The back stop 3, comprising preferably a cylndrical rod, is loosely mounted in apertures 9, Which are considerably larger in diameter than the back stop.

The gummy deposit accumulates at the point of contact 10, either on the armature or the back stop, or both. Upon the armature moving forward in the osition shown in Fig. 1, the back stop 3, f stuck to the armature, is carried along with the latter until the back stop strikes the opposite side upon of the apertures 9. The armature, having gathered momentum, and the magnetic pull having increased due to the shortening of the magnetic gap, will continue to move for- Ward, breaking the adhesion ,between itself and the back stop.

Sticking of message register armatures due to the gummy deposit has been a serious problem involving considerable loss to telephone companies, both on account of failure to register calls and the cost of frequently cleaning large numbers of registers. This problem has been satisfactorily solved by the present invention.

What is claimed is:

1. In an electromagnetic device, an armature, an electromagnet for actuatin said armature and a loosely mounted bac -stop for said armature which is adapted to rotate through a small angle when engagcd by said armature.

2. An electromagnetic device comprising an electromagnet, an armature and' a, cylinsaid armature, said back-stop being mounted dricai back-stop for said armature, said in apertures of a diameter appreciably back-stop being mounted in bearin s havlager than said back-sto o ing a larger diamete' than said bac -stop. n Witness Whereof, I fiereunto subscribe 5 3. In m electromagnetic device, an. armzmy namethis 81st day of December, A. D.,

tu'evan electromagnet for actuating smidl 1920. srmature, pnd a cylindrical back-stop for CLYDE H. WHEELER. 

